African fruit 'brightest' thing in nature but does not use pigment to create its extraordinary col

This odd fruit have really extraordinary iridescent colours that are not the result of pigmentation.
Indeed, Pollia condensata fruit, does not get its blue colour from pigment but instead uses structural colour – a method of reflecting light of
particular wavelengths.

In the forests of central Africa, there’s a plant that looks like it’s growing its own Christmas decorations. Shiny baubles sprout from between
its leaves, shimmering in a vibrant metallic blue. Look closer, and other colours emerge – pinpricks of red, orange, green and violet. It looks as
if Seurat, or some other pointillist painter, had turned their hand to sculpture.

But these spheres, of course, are no man-made creations. They’re fruit. They are the shiniest fruits in the world. Actually, they are the shiniest
living materials in the world, full-stop.

Most colours around us are the result of pigments. However, a few examples in nature – including the peacock, the scarab beetle....

....and now the Pollia condensata fruit – use structural colour as well. Fruits are made of cells, each of which is surrounded by a cell wall
containing cellulose. However, the researchers found that in the Pollia condensata fruit the cellulose is laid down in layers, forming a chiral
(asymmetrical) structure that is able to interact with light and provide selective reflection of only a specific colour. As a result of this unique
structure, it reflects predominately blue light.

The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. The
bright blue coloration of this fruit is more intense than that of any previously described biological material.

Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking
pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light
from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been observed in a single
tissue.

Evolutionary theory states that specific traits within an organism or species "evolved" through a process of natural selection. This is a
hypothetical process whereby randomly occurring mutations are "locked" in if they provide some kind of advantage to the species.

However, having read the article explaining the physics behind this particular plants ability to refract light of a specific frequency, I have to
admit to being somewhat stumped as to how and why all the necessary individual sub-components evolved separately and yet were ALL available exactly
when the plant required the ability to refract light with a blue frequency component.
After all, this refraction "trick" is a highly complex process and reliant on every sub-component having already evolved at some earlier time, and
successfully stored and retained, within the plants genetic structure. So if the sub-components individually (presumably) provide little or no
significant survival value to this species, then one has to ask the following questions:
(1) why did the sub-components evolve in the 1st place ?
(2) once evolved, why were they retained within the genetic framework ?

Originally posted by AnonUK
You raise a very good point, How does an item evolve in separate stages but all at the same time.

Have you seen any thing else like this?

Two other examples immediately come to mind ... both in us humans:
(1) The ear is a complex mechanical structure relying on numerous individual sub-components working together perfectly to enable pressure waves from
the outside being guided to a inner flexible membrane ... that together with other mechanical components, eventually converts the pressure wave into
an electrical signal.
(2) The eye is another highly complex structure incorporating moving/flexing sub-components that are capable of manipulating and processing light
according to optical laws ... eventually converting a photonic impulse into an electrical signal.

Both the above examples depend on their very function (and existence) on previously evolved sub-components.
Again, the question can be asked as to what process caused these individual sub-components to evolve and be genetically stored until every required
piece was available to produce the finished product.

The same goes for birds like crows.
To us they look black and all the same.
To the crows they look each different.
It is done in the same way, without pigments in the feathers, and crows can see a bit more in the UV range

Why does Pollia have such bright fruit? Here’s a clue: you can’t eat them. Well, you can eat them, but there would be no point, because they
provide next to no nourishment. They’re practically a dry seed-filled husk. Here’s another clue: Pollia grows in the same regions as another
plant, Psychotria peduncularis, which also produces blue berries.

The team thinks that Pollia is mimicking the tasty blue fruits of its neighbour, tempting birds with the promise of tasty pulp, but rewarding them
with nothing but seeds to carry. Alternatively, birds could collect the fruits to decorate their nests, or to use in mating displays. Either way,
Pollia gets a free ride, and avoids having to spend energy on making sweet, nourishing tissues. It’s an evolutionary triumph of style over
substance.

Although using animals for dispersal is a strategy common to many plants, most are forced to devote precious calories to produce a sweet, fleshy pulp.
This one, however, is able to spread its seeds simply by showing its true iridescent colors.

Why does Pollia have such bright fruit? Here’s a clue: you can’t eat them. Well, you can eat them, but there would be no point, because they
provide next to no nourishment. They’re practically a dry seed-filled husk. Here’s another clue: Pollia grows in the same regions as another
plant, Psychotria peduncularis, which also produces blue berries.

The team thinks that Pollia is mimicking the tasty blue fruits of its neighbour, tempting birds with the promise of tasty pulp, but rewarding them
with nothing but seeds to carry. Alternatively, birds could collect the fruits to decorate their nests, or to use in mating displays. Either way,
Pollia gets a free ride, and avoids having to spend energy on making sweet, nourishing tissues. It’s an evolutionary triumph of style over
substance.

Although using animals for dispersal is a strategy common to many plants, most are forced to devote precious calories to produce a sweet, fleshy pulp.
This one, however, is able to spread its seeds simply by showing its true iridescent colors.

That is very interesting...pure colours usually have a specific and enhancing nutritional value, that in itself, is related to colour
perception in the species that eat it. This, on the other hand, relies on the bird's eye for 'shiny', purely decorative in it's purpose. How
incredibly fascinating!

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